Mining cutter bit having spring biased detent means



Feb. 13, 1962 J. T; BOWEN 3,021,124

MINING CUTTER BIT HAVING SPRING BIASED DETENT MEANS Filed Dec. 17. 1956 A &

- 2 if; U 42 3 l8 INVENTOR @295, JOHN T. BOWEN ATTORNEY 6 i rted 3,@Zl,l24 Patented Feb. 13, 1962 3,ll2l,l24 CUTTER BET HAVF lG Ellltlhlt? BEAED DETENT MEANS Eohn T. Bowen, La Habra, Caliih, assignor to Union Carbide Corporation, a corporation of New York Filed Dec. 37, 1%55, Ser. No. 628,659 5 Claims. (Cl. 262-3$) This invention relates to mining machines and more particularly to the cutting means thereof.

On various types of mining machinery, e.g. continuous, remotely guided coal cutting and loading machines, it is necessary to provide easily replaceable cutter bits which contact the earth material being cut. Heretofore, such bits have been retained in supports such as cutter blocks or chains by set screws, wedges, dowel pins or latching devices carried by such supports. Such retainers generally have one or all of the following serious faults: (a) due to vibration and heavy loads, the bits work loose and are lost, ([2) elaborate tools are required to insert or remove the bits, the retainer mechanisms Wear out, the retainers become corroded or fouled with dirt thus making the bits difficult to remove.

This invention comprises a catch which is carried entirely by the bit itself and replaced therewith. The support is provided with means having a simple 'hole or cavity to engage such catch. it has been shown by field tests on continuous coal cutting machines, that ample retaining force is provided by such catch and that the bits are not lost in use. Furthermore, the bits can be quickly and easily inserted and removed by hand, or with a simple lever. Since the inexpensive retainer mechanism of the invention is used only once and is then discarded with the worn bit, wear, fouling and corrosion are avoided.

Specifically this invention comprises: a ball or bullet which is located by a crimped shoulder in a blind hole in the bit shank; a spring tending to push the ball outward; a mounting piece having a mating hole or cavity which engages the ball or bullet; the purpose of the inven tion being to retain the bit in the mounting piece against cutting force and yet allow it to be easily installed and removed.

A further advantage of the invention arises from the simplicity of the retainer mating cavity and socket which need be provided in the mounting block or chain. Thus, design of these important parts is greatly simplified with resulting savings in space and cost.

In the drawings:

FIG. 1 is a fragmentary plan view of a bore-mining machine in operation in a mine that is shown in horizontal section;

FIG. 2 is an enlarged fragmentary plan view of a cutter head comprising the invention;

FIG. 3 is an enlarged fragmentary view in cross-section taken on line 33 of FIG. 2; and

FIG. 4 is a transverse cross-section of a modification of the invention.

FIG. 5 is an enlarged fragmentary view in cross-section showing the crimpcd shoulder.

As shown in P16. 1, a bore-mining machine 10, such as that disclosed in the patent application (which is owned by the assignee of the present application) of Alspaugh et al., Serial No. 353,932, filed May 11, 1953, now Patent No. 2,826,932, is provided with a plurality of rotary front cutter heads 12 having forwardly projecting bitsupports 14- that are provided with sockets 16 of rectangular cross-section for receiving the rectangular shanks it? of bits 25. Adjacent each socket is a rear partly cylindrical recess 22 in which is mounted a similarly shaped hardened steel insert that is keyed in place by a transverse bronze pin 26 the ends of which are riveted.

The insert is provided with a bore 28 forming an annular recess for partially receiving a ball detent Sit that is carried by the shank of such bit.

The ball detent is located in a blind bore 32 provided therefor in the shank, between an annular stop 3% formed by upsetting the metal at the edge of the bore 32 at the outer end of such bore, and a helical steel Wire spring 36 positioned within such bore behind said ball detent. The bit and ball detent, thus, provide a quickly replaceable unit that may be snapped in place in the head or other support, and as quickly and easily removed as a unit.

it is necessary that the shank of the bit fit somewhat more closely in the socket than when the bit is to be retained with a set screw, because the ball extends only a limited distance out from the side of the bit. If the loose ness of fit is greater than the extension of the ball, the bit would not be retained. Also, it is important that the catch hold the bit in place with suitable means such as a shoulder 38 that limits movement of the shank in the socket inwardly thereof.

As shown in FIG. 4 a body 44 of resilient material, such as rubber is used to urge the ball detent 3% outwardly instead of a wire spring. The rubber body 40 can be made to provide greater urging *force than metal in the small space that is available.

Bit assemblies made according to the invention do not ordinarily foul with coal dust during the life of a bit. This feature of constant replacement of the catch also usually prevents any difiiculty with ball wear, as is' the case when the catch is located in the socket in the support. The halls are preferably made of brass or stainless steel in order to prevent rusting.

The catch is located on the back side of the polygonal shank of the bit because normal loads tend to keep the bit in contact with the holder on the back side, thereby making the catch more effective. However, it might be located on either side or on the front thereof. from shoulder 42 of the illustrated bit provides a shelf under which a simple lever can be inserted to pry the bit from its support. The cutting edge of the bit is provided with an insert of hard metal such as tungsten carhide to increase the life thereof.

While I have no actual figures concerning relative down time resulting from use of the invention compared with prior conventional holding arrangements, I have reason to believe that loss of bits made according to the invention during operation is no worse and may be better than the losses with prior conventional bits. Loss of bits involves not only hit replacement costs, but also a considerable loss or" production in backing the machineimportant where several bits are used in clusters or closely spaced in series. This problem is usually encountered in continuous miner cutter head construction. Locating the catch in the bits according to the invention makes it possible to more closely space the bits in a holder compared to location of the catches in the holder, inasmuch as the holder only requires a simple recess to retain each bit in place.

What is claimed is:

1. In a mining machine, the combination with a driven member having at least one elongated socket of polygonal cross section provided with a lateral recess, of a replaceable cutter bit for said mining machine having an elongated shank of polygonal cross section shaped to fit said socket and longitudinally insertable therein and re movable therefrom, said cutter bit also having a shoulder bearing against said member defining the limit of ion: gitudinal movement of said shank into such socket, said shank having a lateral blind bore facing said recess, said bore having an annular shoulder adjacent its outer end, a ball detent mounted within said bore for limited movement by virtue of such shoulder, axially of the bore, toward and away from such recess, a compression spring in such bore, urging said ball detent toward its outer limit into contact with such annular shoulder and thus effectively sealing such bore against the entrance of water and dirt back of said ball detent, said spring being yieldable when said ball detent is pressed into such bore by engagement with the wall of said socket when said shank is inserted in or removed from said socket, and acting as the sole means to retain said bit in operational position by pressing said ball detent into said recess, holding said shoulder against said member, which latch can be quickly released by simply withdrawing said bit from said socket, said detent and urging means mounted in said shank being cliscardable as a unit when said cutter bit is dulled, and automatically replaceable when a similar unit with a sharp cutter bit is substituted, whereby avoidance of corrosion or fouling of said detent and urging means is periodically and automatically reassured.

2. In a mining machine, the combination with a driven member having at least one elongated socket provided with a lateral recess, of a replaceable cutter bit for said mining machine having an elongated shank shaped to fit said socket and longitudinally insertable therein and removable therefrom, said cutter bit also having a rear shoulder bearing against said member defining the limit of longitudinal movement of said shank into such socket, said shank having a lateral bore facing said recess, said bore having an annular stop, a ball detent mounted within said bore for limited movement axially of the bore toward and away from such recess, a compression spring in said bore urging said ball toward its outer limit into contact with such annular stop to effectively seal such bore against the entrance of water and dirt back of said ball detent, said spring being yieldable when said ball is pressed into {such bore by engagement with the wall of said socket lwhen said shank is inserted in or removed from said socket, and acting as the sole means to retain said bit in operational position by pressing said ball into said recess, holding said shoulder against said member, which latch can be quickly released by simply withdrawing said bit from said socket, said cutter bit with its spring pressed detent being discardable as a unit when it is replaced.

3. In a coal mining machine, a driven bore-cutting head having a plurality of closely spaced similarly shaped elongated sockets each of which is provided with a lateral recess, of a plurality of similar replaceable and interchangeable cutter bits for said coal mining machine, each of said bits having an elongated shank shaped to fit said socket and longitudinally insertable therein and removable therefrom, said cutter bit also having a shoulder bearing against said member defining the limit of longitu'dinal movement of said shank into such socket, said shank having a lateral bore facing said recess, said bore having an annular stop, a ball detent mounted within said bore for limited movement axially of the bore toward and away from such recess, a spring in said bore urging said ball toward its outer limit into contact with such annular stop to effectively seal such bore against the entrance of water and dirt back of said ball detent, said spring being yieldable when said ball is pressed into such bore by engagement with the wall of said socket when said shank is inserted in or removed from said socket, and acting as the sole means to retain said bit in operational position by pressing said ball into said recess, holding said shoulder against said member, which latch can be quickly released by simply prying said bit out of said socket, and replaced by inserting the shank of another hit in said socket, whereby when said bits become worn due to the operation of said machine they can be readily and quickly discarded and replaced with similar bits by merely snapping out the worn bits and snapping in fresh ones.

4. A mining machine-cutter bit having a polygonal shank provided with a lateral bore, said bore having an annular stop, a detent carried by said bore for limited movement axially therein, a spring in such bore urging said detent towards its outer limit into contact with such annular stop to effectively seal such bore against the enrance of water and dirt back of said ball detent, said spring being yieldable to allow said detent to be forced inwardly into said bore, said bit also having a shoulder spaced from said detent for limiting inward movement of the shank in the socket of a support therefor, the entire bit and detent assembly being discardable after use.

5. A mining machine-cutter bit that is discardable after use, said bit having a rectangular shank provided with a. lateral bore in the rear thereof, said bore having an annular stop, a ball detent carried by said bore for limited movement axially therein, a compression spring in such bore urging said ball detent rearwardly towards its outer limit into contact with such annular stop to effectively seal such bore against the entrance of water and dirt back of said ball detent, said spring being yieldable to allow said ball detent to be forced inwardly into said bore, said bit also having a rear shoulder spaced from said ball detent for limiting inward movement of the shank in the socket of a support therefor, said spring and detent being discardable as a unit when the bit is thrown away.

References Cited in the file of this patent UNITED STATES PATENTS 490,685 Schilling Ian. 31, 1893 509,407 Taylor Nov. 28, 1893 750,182 Furbish Jan. 19, 1904 883,076 Askins Mar. 24, 1908 994,804 Wahlstrom June 13, 1911 1,392,220 Quint Sept. 27, 1921 1,430,669 Morgan Oct. 3, 1922 2,372,266 Frank Mar. 27, 1945 2,521,039 Phipps Sept. 5, 1950 2,747,852 Krekeler May 29, 1956 FOREIGN PATENTS 683,340 Great Britain Nov. 26, 1952 

